Increased capacity spherical lined bearings

ABSTRACT

A rotary system and method to control feathering movement of a rotor blade. The system having a yoke arm configured to rotate a rotor blade. A first bearing and a second bearing are utilized to secure the rotor blade to the yoke arm and are configured to restrict longitudinal and transverse movement, while allowing feathering movement of the rotor blade relative to yoke arm.

BACKGROUND 1. Field of the Invention

The present application relates generally to rotary systems, and more specifically, to a tail rotary system having spherical lined bearings.

2. Description of Related Art

Conventional tail rotors are well known in the art for effectively controlling yaw movement of a rotary aircraft. The tail rotor utilizes a plurality of rotor blades for creating thrust, and during flight, the rotor blades tend to feather, thereby creating an undesired movement that could cause the tail rotor to fail.

In some embodiments, conventional tail rotary systems include rotor blades that rigidly attach to the yoke arms. These embodiments are effective in restricting rotor blade feathering movement; however, the embodiments are prone to failure due to the blade feathering stresses exerted on the yoke arm.

Although great strides have been made in the field of tail rotary systems, many shortcomings remain.

DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of a rotary aircraft utilizing a rotary system of the present application;

FIG. 2-3 are oblique views of a tail rotor of the rotary aircraft;

FIG. 4 is a partial oblique view of a yoke arm of the tail rotor of FIG. 2;

FIG. 5 is a cross-sectional view of the yoke arm of FIG. 4 taken at V-V;

FIG. 6 is a cross-sectional view of the yoke arm of FIG. 4 taken at VI-VI;

FIG. 7 is a top view of a spherical bearing of FIG. 4;

FIGS. 8A and 8B are cross-sectional views of the spherical bearing of FIG. 6 shown operably associated with a mast; and

FIG. 9 is a flow chart depicting the preferred method.

While the system and method of the present application are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of the system and method are provided below. It will of course be appreciated that in the development of any actual embodiment, numerous implementation-specific decisions will be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

The tail rotary system of the present application overcomes common disadvantages associated with conventional tail rotors by providing effective means for controlling feathering forces created by the rotor blades attached thereto during flight. Specifically, the tail rotor includes one or more bearings for securing the rotor blades to a yoke arm of a hub retention system. The bearings are aligned in a linear fashion so as to prevent longitudinal and transverse movement of the blade relative to the yoke arm, yet allowing feathering movement of the rotor blade. The bearings also include cutouts selectively positioned in the bearing housing for increasing feathering movement.

The tail rotary system of the present application will be understood, both as to its structure and operation, from the accompanying drawings, taken in conjunction with the accompanying description. Several embodiments of the system are presented herein. It should be understood that various components, parts, and features of the different embodiments may be combined together and/or interchanged with one another, all of which are within the scope of the present application, even though not all variations and particular embodiments are shown in the drawings. It should also be understood that the mixing and matching of features, elements, and/or functions between various embodiments is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements, and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise.

Referring now to the drawings wherein like reference characters identify corresponding or similar elements throughout the several views, FIG. 1 is a side view of a rotary aircraft 101 utilizing the tail rotary system of the present application. Although depicted with the exemplary type of rotary aircraft 101, it will be appreciated that the features disclosed herein are easily adaptable for use with other types of rotary aircraft.

Rotary aircraft 101 comprises a main rotary system 103 positioned above fuselage 105 for rotating two or more rotor blades 107. The main rotary system 103 is controlled with a plurality of controllers carried within fuselage 105. During flight, the cyclic controller 109 and/or pedal 111 are manipulated to create vertical, horizontal, and yaw flight direction. Aircraft 101 is further provided with a tail rotor 113 that creates yaw movement during flight. A detailed description of tail rotor 113 is provided below.

Turning next to FIGS. 2 and 3 in the drawings, oblique views of tail rotor 113 according to the preferred embodiment of the present application are shown. In the exemplary embodiment, tail rotor 113 includes four rotor blades 201; however, it will be appreciated that tail rotor 113 is easily adaptable for use with more of less blades in an alternative embodiment. It should be understood that for clarity, one of the four blades is removed to illustrate the bearings associated with the tail rotor. Blades 201 are configured to couple with a hub retention member 203 having four yoke arms 205, which in turn is rotatably attached to a mast 207 and an engine transmission 209.

Tail rotor 113 is further provided with two or more bearings: a first bearing 211 and a second bearing 213, both bearings being configured to allow slight feathering movement of the rotor relative to the yoke arm. In the preferred embodiment, bearings 211 and 213 are spherical bearings that sit flush with an upper surface and a lower surface of yoke arm 205; however, it will be appreciated that other types of bearings and devices could be used in lieu of the preferred embodiment. As is described more fully below, the spherical bearings allow for slight feathering motion of the rotor blades, which provides significant advantageous over conventional tail rotors, namely tail rotors having rotor blades rigidly attached to the yoke arm.

Referring specifically to FIG. 3, yoke arm 205 has length extending along a longitudinal axis A1 and both bearings 211 and 213 have centerlines C1 and C2, respectively, that are aligned in a linear fashion such that both centerlines C1 and C2 intersect with the longitudinal axis A1 of yoke arm 205.

In FIG. 4, a partial oblique view of yoke arm 205 is shown. FIG. 4 provides further illustration of the bearings according to the preferred embodiment of the present application. Tail rotor 113 preferably includes two bearings for securing the rotor blade to the yoke arm; however, it will be appreciated that alternative embodiments could include additional bearings in lieu of the preferred embodiment. The two bearing configuration provides means for restricting transverse movement of the rotor blades in direction D1 and longitudinal movement in direction D2; however, the bearings are configured to allow slight feathering movement of the rotor blades in direction D3 during flight. These features are achieved due to the alignment of the bearings relative to the yoke arm longitudinal axis A1, as described above.

In FIG. 5, a cross-sectional view of yoke arm 205 is shown taken at V-V of FIG. 4. In the preferred embodiment, both bearings 211 and 213 are spherical bearings, which allow pivoting movement in direction D3 to compensate for feathering. Bearing 211 comprises of a spherical ball 501 rotatably engaged with a housing 503, and likewise, bearing 213 comprises a spherical ball 505 rotatably engaged with a housing 507. Both bearings 211 and 213 include passages 509 and 511, respectively, as means for securing the blade thereto. In the preferred embodiment, housing 503 extends the entire thickness length of yoke arm 205, specifically, from a top surface 513 to a bottom surface 515. This feature increases the contact surface area between housing 503 and spherical ball 501.

FIG. 6 is a cross-sectional view of yoke arm 205 taken at VI-VI of FIG. 4. Bearing 211 is further provided with four cutouts extending from the top and bottom surfaces of housing and inwardly into housing 503. The cutouts are preferably contoured to match the outer contouring of the attachment means received by passage 509. It should be understood that the cutouts allow additional feathering movement of the rotor blades in direction D3, which in turn greatly increases the efficiency of bearing 211. As is shown, bearing 211 preferably comprises four cutouts: a first cutout 601 and a second cutout 603 extending from a top surface 605 of housing 503, and a third cutout 607 and a fourth cutout 609 extending from a bottom surface 611 of housing 503.

In FIG. 7, a top view of bearing 211 is depicted. FIG. 7 further illustrates the contouring of cutouts 601 and 603. In the preferred embodiment, cutouts 601 and 603 have a generally circular contouring to match the contouring of the attachment means, i.e., a circular shaft. However, it will be appreciated that cutouts 601 and 603 could easily be manufactured with different geometric contouring in alternative embodiments. It should be understood that the cutouts are selectively machined on outer housing 503 to allow additional pivoting movement of spherical ball 501 in direction D3 (feathering movement), but not in direction D2. It should be appreciated that the combination of bearings 211 and 213 are utilized in conjunction with each other to prevent movement in directions D1 and D2, while allowing pivoting movement in direction D3. The cutouts are utilized to increase pivoting movement of the rotor blades during flight.

In FIGS. 8A and 8B, the bearings are shown operably associated with an attachment means 801, which in the preferred embodiment, is a shaft that extends through passage 509. Attachment means 801 could include a liner placed between the spherical ball 501 and attachment means 801 for providing protection and support. As is depicted in FIG. 8B, phantom lines of attachment means 801 show feathering movement of the rotor blade relative to the yoke arm. It should be understood that attachment means 801 does not come into contact with housing 503.

Referring next to FIG. 9, a flow chart 901 depicting the preferred process is shown. Box 903 shows the first step, which includes attaching a rotor blade to a yoke arm via a first bearing and a second bearing. The next step includes aligning the first bearing and the second bearing on the yoke arm to restrict both longitudinal and transverse movement of the rotor blade relative to the yoke arm, as depicted in box 905. Finally, box 907 shows the last step, which includes allowing pivoting movement of the rotor blade relative with yoke arm to compensate for feathering during flight.

It is apparent that a system and method with significant advantages has been described and illustrated. The particular embodiments disclosed above are illustrative only, as the embodiments may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. It is therefore evident that the particular embodiments disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the application. Accordingly, the protection sought herein is as set forth in the description. Although the present embodiments are shown above, they are not limited to just these embodiments, but are amenable to various changes and modifications without departing from the spirit thereof. 

What is claimed is:
 1. A method to control feathering movement of a rotor blade, comprising: attaching a rotor blade to a yoke arm via a first bearing and a second bearing; aligning the first bearing and the second bearing on the yoke arm in a linear fashion; limiting feathering to a first direction and a second direction; and allowing pivoting movement of the rotor blade relative with yoke arm to compensate for feathering during flight.
 2. The method of claim 1, further comprising: restricting both longitudinal and transverse movement of the rotor blade relative to the yoke arm with the first bearing and the second bearing.
 3. The method of claim 1, further comprising: aligning a centerline of the first bearing and a centerline of the second bearing with a longitudinal axis of the yoke arm.
 4. A rotary system, comprising: a yoke arm; a rotor blade; and a first bearing carried by the yoke arm and configured to pivotally secure the rotor blade to the yoke arm and to allow feathering movement of the rotor blade relative to the yoke arm during flight in only a first feathering direction and a second feathering direction. 